Another 505 battery grump: I got mine at the end of October. I'd never even tried the audio functionality. The maximum number of page turns I ever got out of it on one charge was 503. It took me four full charges to read one 1700-page book (medium type size). This seemed unacceptable, so I called Sony and spoke with a PRS tech rep who didn't appear to know anything about the battery. He told me I wouldn't get anywhere near 7500 pages, and if I got 500, that was good.
Now the box says "up to 7500" and is footnoted "actual battery life may vary based on usage patterns." But if plain old reading - no tunes - means I only get 1/15th of the advertised battery life, I consider that some serious misrepresentation.
I figured I had a faulty unit. Sony would have repaired it for me, but couldn't promise I'd get it within three weeks. So I took my receipt and 505 back to Borders; they kindly exchanged it for a new one today. I've topped up the battery, and we'll see how things go this time.
When I put it down, I'll activate the "device shutdown" feature (I did this with the first unit):
Settings --> Advanced Settings --> Device Shutdown ... then press the bookmark function to complete the shutdown process.
To restart, turn the unit on using the power slide, as you normally would. Using the power slide to turn the device off does not shut the device down!
I'll follow these battery instructions from the previous post:
Batteries with fuel gauge (laptops) should be calibrated by applying a deliberate full discharge once every 30 charges.
... otherwise topping up the 505 after partial discharges.
And I'll let you know what happens.